Sonar imaging systems use a technology referred to as synthetic aperture sonar (SAS). Sonar imaging systems utilize an assembly of sonar transducers, called an array, which transmit and receive acoustic pulses called “pings.” The array mounts to a mobile platform, such as a submarine. Movement of this platform results in the array moving along a line called a track. SAS systems combine the results of multiple pings transmitted from an array at different times to form a high-resolution image. Summing these pings using a beamforming technique allows production of the image. To ensure image accuracy, the SAS system must have a value for array displacement along the track between pings.
It is a problem known in the art that SAS systems may be inaccurate due to a lack of ability to determine displacement along the track because the platform is controlled separately. Since SAS systems use displacement compensation algorithms to adjust for the movement of the array when producing the image, such displacement values are critical to ensure quality of the image. The system must perform these adjustments in real time to allow real time display of the images. Currently, the position can only be estimated in two dimensions, limiting the accuracy of the SAS image. Furthermore, SAS systems require accurate speed of sound measurements to use beamforming techniques. Current SAS systems assume a speed of sound based on previous data, but cannot simulate a speed of sound to evaluate the accuracy of these assumptions.
There is an unmet need in the art for highly accurate methods of calculating the displacement of an array and incorporating this critical data into SAS imaging.
There is a further unmet need in the art for an SAS system capable of processing simulated data to ensure the accuracy of an assumed speed of sound.